Water transport in the immature rabbit collecting duct

Bonilla–Félix, Melvin; Vehaskari, V. Matti; Hamm, L. Lee

doi:10.1007/s004670050572

Cited by 26 publications

(6 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2, the adult tubules had a larger increase in water permeability in response to ADH than did the neonatal tubules (260.1 ± 29.5 vs. 119.0 ± 12.5 µm/s; P < 0.05, n = 6). These results are comparable to previously reported findings (5,19,36).…”

Section: Camp Generationsupporting

confidence: 92%

Antidiuretic hormone resistance in the neonatal cortical collecting tubule is mediated in part by elevated phosphodiesterase activity

Quigley

Chakravarty

Baum

2004

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

Neonates cannot concentrate their urine to the same degree as adults. One of the key factors in concentrating the urine is the renal collecting duct osmotic water permeability (Pf) response to antidiuretic hormone (ADH). Neonatal cortical collecting ducts have a blunted Pf response to ADH compared with adult tubules (Pf: 119.0 +/- 12.5 vs. 260.1 +/- 29.5 microm/s, P < 0.05). We found that the phosphodiesterase activity in the neonatal collecting ducts was higher than that in the adult collecting ducts (3,970 +/- 510 vs. 2,440 +/- 220 cpm.microg tubular protein-1.20 min-1, P < 0.05). After pretreatment of in vitro microperfused tubules with the nonspecific phosphodiesterase inhibitor IBMX (10-6 M in the bath), the Pf response to ADH in neonatal collecting ducts was 271.4 +/- 51.7 microm/s, which was identical to that of the adult collecting duct [315.3 +/- 31.3 microm/s, P = not significant (NS)]. Rolipram, a specific type IV phosphodiesterase inhibitor, lowered the elevated phosphodiesterase activity in the neonatal tubules to that in the adult tubules (2,460 +/- 210 vs. 2,160 +/- 230 cpm.microg tubular protein-1.20 min-1, P = NS). Neonatal tubules pretreated with rolipram (10-5 M) in the bath also had a Pf response to ADH that was comparable to that of the adult tubules (258.2 +/- 17.0 vs. 271.4 +/- 32.6 microm/s, P = NS). Thus the elevated phosphodiesterase activity in the neonatal tubules appears to be due to an increase in type IV phosphodiesterase activity. Hence, one of the key factors in the decreased ability of neonates to concentrate their urine is overactivity of phosphodiesterase in the cortical collecting duct that blunts the neonatal collecting duct Pf response to ADH.

show abstract

Section: Camp Generationsupporting

confidence: 92%

Antidiuretic hormone resistance in the neonatal cortical collecting tubule is mediated in part by elevated phosphodiesterase activity

Quigley

Chakravarty

Baum

2004

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

show abstract

“…Neonatal CT water permeability did not increase in response to vasopressin to the same extent as that seen in the adult [312][313][314][315]. Studies have shown that the phosphodiesterase activity is greater in the neonatal collecting tubule [313].…”

Section: Development Of Urinary Concentration and Dilutionmentioning

confidence: 57%

“…The response of the collecting tubule to vasopressin has been examined in vitro [312][313][314][315]. Neonatal CT water permeability did not increase in response to vasopressin to the same extent as that seen in the adult [312][313][314][315].…”

Section: Development Of Urinary Concentration and Dilutionmentioning

confidence: 83%

Renal Tubular Development

Baum

2014

Pediatric Nephrology

View full text Add to dashboard Cite

The nephron is faced with the enormous task of maintaining a constant composition and volume of the extracellular fluid. The amount of electrolytes and water ingested and absorbed must be eliminated, and the waste products from metabolism must also be excreted. This challenge is all the more complex as our dietary intake is quite variable from day to day. Despite this variable intake, there is virtually no change in the volume or composition of the extracellular fluid volume from day to day.There are two possible ways that our kidney could balance ingestion and excretion. The kidney could be a secretory organ where all the excess solutes and water ingested would be excreted by tubular secretion. This would be very inefficient and require an enormous amount of energy. In addition, in times of a disturbance in the extracellular fluid volume such as a high salt intake or volume loss from diarrhea, the regulatory systems necessary to maintain a constant extracellular fluid volume and composition while excreting waste products would be very complex. On the other hand, the kidney could filter an enormous quantity of extracellular fluid, which would be very efficient in removing waste products, and reclaim the desired salt, organic solutes, and water. With volume depletion, a greater fraction of salt and water could be reabsorbed, and when one has a dietary indiscretion such as the salt intake from a pepperoni pizza, there could be a reduction in sodium reabsorption leading to an increase in excretion to bring us back into balance. The mammalian kidney actually uses both mechanisms to perform its job which is necessary for our survival on land. The adult kidney filters~150 l of isotonic fluid a day and reclaims most of it, leaving the waste produces to be excreted in about 1.5 l of urine. In addition, there are secretory processes for solutes such as organic anions and cations in the proximal tubule and secretory mechanisms to excrete the excess acid generated from metabolism in the distal nephron which aid in maintaining homeostasis.To accomplish the remarkable task of reclamation of the necessary solutes and water to maintain a constant composition of the extracellular fluid volume, the mammalian kidney has evolved into a highly specialized organ with thousands of units called nephrons. Each human kidney has approximately one million nephrons. Each nephron is a tube consisting of epithelial cells and is divided into 12 specialized segments as shown in Fig. 1. The epithelial cells allow for the vectorial transport of solutes. The proximal tubule is responsible for the bulk reclamation of solutes and water and for the secretion of organic cations and anions. Approximately two-thirds of the glomerular filtrate is reabsorbed by the proximal tubule in an isotonic fashion. Virtually all of the organic solutes, as well as the majority of bicarbonate, phosphate, and chloride, are reabsorbed in this segment. The proximal tubule is divided into S 1 , S 2 , and S 3 segments based on the rates of transport of some solutes and mor...

show abstract

“…In the later process of dif-ferentiation, it develops a functional barrier, so that different fluid compositions are found at the luminal and basal sides [26,27]. It is unclear how far a change in the electrolyte environment is able to influence the development of the epithelium.…”

Section: Discussionmentioning

confidence: 99%

Embryonic Renal Collecting Duct Cell Differentiation Is Influenced in a Concentration-Dependent Manner by the Electrolyte Environment

et al. 2001

View full text Add to dashboard Cite

Background: During kidney development, the embryonic collecting duct (CD) epithelium develops into a heterogeneously composed epithelium consisting of principal and intercalated cells. It is unknown by which molecular mechanism the different cell types arise. We have experimental evidence that the electrolyte environment is involved in the process of terminal cell differentiation. Methods: Embryonic CD epithelia from neonatal rabbit kidneys were microsurgically isolated and maintained in gradient perfusion culture for 13 days under serum-free conditions. Controls were maintained in the same medium (Iscove’s modified Dulbecco’s medium; IMDM) on basal and luminal sides. Experimental series were performed with IMDM only on the basal side, while on the luminal side IMDM with increasing concentrations of NaCl was used. Finally, the development of principal and intercalated cell features was registered by immunohistochemical labeling with markers specific for adult CD cells. Results: Immunohistochemical markers show that the differentiation pattern is quite different when the embryonic CD epithelia are cultured in IMDM only as compared with specimens kept in IMDM supplemented with 3–24 mmol/l NaCl on the luminal cell side. First signs of changes in development were seen when low doses of 3–6 mmol/l NaCl were added. Conclusions: We conclude that facultative protein expression in embryonic CD epithelium is influenced by the electrolyte environment and starts to be upregulated after administration of unexpectedly low doses of 3–6 mmol/l NaCl added to the luminal perfusion culture medium and increases in a concentration-dependent manner.

show abstract

Water transport in the immature rabbit collecting duct

Cited by 26 publications

References 24 publications

Antidiuretic hormone resistance in the neonatal cortical collecting tubule is mediated in part by elevated phosphodiesterase activity

Antidiuretic hormone resistance in the neonatal cortical collecting tubule is mediated in part by elevated phosphodiesterase activity

Renal Tubular Development

Embryonic Renal Collecting Duct Cell Differentiation Is Influenced in a Concentration-Dependent Manner by the Electrolyte Environment

Contact Info

Product

Resources

About